Regarding BTC, just because a single transistor could run faster doesn’t mean it’s necessarily a good candidate for BTC mining (eg. Most mass miners use ASICs,

Regarding BTC, just because a single transistor could run faster doesn’t mean it’s necessarily a good candidate for BTC mining (eg. Most mass miners use ASICs, not the fastest CPUs because they care about the fastest way to check LOTS of candidate hashes in parallel, not a single one at an extremely high rate). A light based transistor would either require all of the rest of the system run on light or it would have to be mated to silicon/electrical hardware which would slow down the clock rate of the system. BTC Mining adjusts based on difficulty. IIRC (I haven’t looked into the specifics in a few years) the protocol will adjust so a block should be mined every 10 mins or so. If there is a massive leap in hardware capabilities, the protocol automatically throws A LOT more difficulty at the mining problem. One way to crash BTC using a massive hardware advance: dominate the mining for ~ 2 weeks, long enough until until the mining difficulty is adjusted upwards and stop mining. Much higher difficulty + only older hardware doing the work = very slowly processed blocks and a growing backlog of transactions. Eventually the protocol would reduce the difficulty to match higher block transaction rates, but the attack could be maintained by thrashing the miner on/off just after the difficulty is adjusted upwards/down.